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cuAP. XXI.] INSECTS. 469
Longicorns of the Tropics, are almost as well known as those of
the Temperate Zones, the Staphylinidae, the smaller Elateridse,
and many other obscure and minute groups, are very imperfectly
represented from extra-European countries. I therefore propose
to examine with some care the distribution of the Butterflies,
and the Sphingina among Lepidoptera, and the following large
and well-known families of Coleoptera :— Cicindelidse, Carabidte,
Lucanidse, Cetoniidse, Buprestidse, and the three families of Lon-
gicorns. These families together contain over 30,000 species,
classed in nearly 3,000 genera, and comprise a large proportion
of the best known and most carefully studied groups. We may
therefore consider, that a detailed examination of their distribu-
tion will lead us to results which cannot be invalidated by any
number of isolated facts drawn from the less known members of
the class.
Range of Insects in Time.—In considering how much weight
is to be given to facts in insect distribution, and what inter-
pretation is to be put upon the anomalies or exceptional cases
that may be met with, it is important to have some idea of the
antiquity of the existing groups, and of the rate at which the
forms of insect life have undergone modification. The geo-
logical record, if imperfect in the case of the higher animals,
is fragmentary in the extreme as regards indications of former
insect life; yet the positive facts that it does disclose are of
great interest, and have an important bearing on our subject.
These facts and the conclusions they lead to have been discussed
in our first volume (p. 166), and they must be carefully weighed
in all cases of apparent conflict or incongruity between the dis-
tribution of insects and that of the higher animals.